1. Field of the Invention
This invention relates to a method for detecting and testing wafers during a semiconductor fabrication process, and more particularly, to a method for detecting and analyzing defects on wafers during the semiconductor fabrication process.
2. Description of Related Art
As a result of the downsizing of the designed line width, to improve and maintain the yield of semiconductor fabrication process has become more and more difficult. Among defects on wafers, the particles and defects are the most critical ones for the yield of semiconductor fabrication process. Hence, how to detect, analyze, and reduce particles and defects are directly related to the improvement of semiconductor fabrication process.
Generally, both patterned and blank wafers need a plurality of steps of before-process inspection. Before the accomplishment, every wafer needs to be inspected to ensure that every fabricating step is correct and precise, for maintaining a good yield. The inspecting steps include inspecting the quantity of particles generated by the apparatuses of fabrication process, such as chemical vapor deposition.
The conventional method for detecting particle defect on wafers before and after applying photoresist by using the scattering principle of laser beams, is to scan an blank wafer and calculate the quantity of particles, and then, to repeat the step again after photoresist is applied, and finally, to obtain the quantity of particle defects within the photoresist and apparatus by calculating the difference between those two quantities of particles. However, the conventional method can only detect the defects caused by particles, but not the defects formed after the exposure and development of the photoresist. Furthermore, some of those particles detected before the photoresist is applied might be covered by the photoresist after coating and cannot be detected, which will leads to a detecting error.